Heart disease is the leading cause of death for both men and women in this country, rising rapidly following menopause. Increased adiposity is implicated in the elevated risk of age-related metabolic disease in women, including heart diseases. The molecular and cell-biological mechanisms underlying the metabolic actions of various hormones and their relationship to adiposity are poorly understood. Advances in epidemiology, biochemistry and histological techniques show that lipid metabolism, particularly the metabolism of atherosclerotic plaque, is correlated with impending heart diseases.
Lehmann et al. (Lehmann K G et al. 1998 Cathet Cardiovasc Diagn 45:191-201) examined chromatic distortion during angioscopy using a quantitative colorimetric system with 2 color coordinates and HSI (hue, saturation, intensity) color space based on the tri-stimulus values mimicking the human color vision. In another study (Lehmann K G, et al. 1997 Circulation 96:3030-3041), their system was utilized to differentiate thrombus based on color. However, the ability of their system to distinguish the color of atherosclerotic plaques, which have a different range of color from thrombus, is not known since this issue has not been investigated. In addition, for the detection of lipid cores under thin fibrous caps (LCTCs), two color coordinates used in these studies would be required to translate to a single coordinate of yellow color intensity.
Miyamoto et al (Miyamoto A et al. 2004. Clin Cardiol 27:9-15) used quantitative colorimetry to study the relation of yellow color saturation with the cap thickness of fibroatheromas, and found an inverse relationship by using color as a continuum rather than a binary measurement (yellow vs. white). In their system, yellow saturation, which is also derived from HSI color space, was used to represent yellow color intensity of plaques. However, yellow saturation may not ideally represent the gradations of yellow color intensity because of its nonlinear nature. In addition, no detailed process of optimization that considers the effects of variables was examined in their system.
Human carotid and femoral arteries are exemplary sites of plaque deposition and maturation, as a result of which a plaque is more likely to fracture and enter the circulating blood. There is a need for rapid, inexpensive and straightforward techniques of measuring and analyzing the condition of human atherosclerotic plaques, and applying such methods to assess the risk of coronary or arterial conditions.